Get ready folks. Itís about to begin. First it will be a UFO report:
"I was looking at the sky when I noticed this light traveling
along that got brighter and brighter. I knew it wasnít an airplane because
there were no red lights. Just a bright light that got incredibly brighter.
It nearly blinded me. It couldn't have been from this world."
We will explain to them that what they saw was an Iridium satellite.
Then the government conspiracy theories will start:
"Have you seen those bright flashes in the night sky? The
government is radiating us with iridium. Itís part of a vast conspiracy
to sterilize males and control population growth."
We will tell them that is hogwash. They will respond by quoting a quatrain
from Nostradamus in which he predicted these events. When they discover
that there are to be 66 of these satellites, they will make the minor
jump from 66 to 666 and tell us how the Antichrist is behind it all.
Mark my words.
Whatís Going On?
The scariest animation
of the year (74K) shows the armada of Iridium satellites in low earth
orbit. Click on image to view. Animation from Iridium company site.
While we wait for these events, letís enjoy this brief window of sanity
and enjoy, or vilify (depending on your viewpoint) this phenomenon. In
the May 1998 issue of Sky & Telescope Philip Chien wrote an excellent
primer on Iridium flares. There are also a number of web sites covering
the subject. Links are provided at the end of this article.
Beginning May 1997 Motorola began launching a series of communications
satellites known by the commercial name Iridium. The satellites have no
association with the element iridium beyond the name. Each satellite has
three antennae. Each antenna is about the size of a typical door in your
home and is is a near perfect mirror. When they are oriented just right
a small portion of the earth will receive an nearly perfect reflection
of the Sun. A perfect "hit" will produce a flash of Ė8 magnitude.
If the Sun were a door sized object it would shine at a bit more than
Ė8 magnitude. This is bright enough to cause dim shadows on
the ground. There are reports that Iridium flares have been visible as
glows in thin cloud-covered skies. However the magnitude drop off is rapid.
A person at the center of the flash can see a Ė8 magnitude event while
someone twenty miles away will only see a Ė4 magnitude (equal to Venus
in brightness) event. Just using the phrase "only as bright as Venus"
to describe a diminished apparition tells you that we are dealing with
a new thing in the night sky.
Show Me The Money
Note: A new RTMC flare photo from John Sanford is here.
The exciting thing is that these flares can be predicted with amazing
accuracy. At the 1998 Riverside Telescope Makerís Conference several predicted
flares were observed by hundreds of observers. One, a Ė7 magnitude event,
drew such a huge cheer from the crowd that it could be heard a mile away.
Stephen Edberg, an RTMC leader, commented that "hearing" the
flares (i.e. the crowd) was nearly as exciting as seeing them. Another
flare on the same night only reached Ė4 magnitude but was accented by
a bright meteor during itís passage.
of a -4 magnitude flash from an Iridium satellite and a bright meteor passing
through Cygnus as observed at RTMC on May 24, 1998. Animation copyright
by Russell Sipe. Background stars from The Sky Level IV by Software Bisque.
The Good, or the Bad and Ugly
On any given night an observer could see a half dozen or more of these
flares. Most will be dimmer than the 8 monsters. You can expect to
see a 6 magnitude or greater flare once or twice a week if you know
where to look.
Is Motorola rubbing our noses in it? Their new portable phone is
called the fLaRe.
The flares can be a disruptive element to amateur astronomers conducting
wide field astrophotography. The most dedicated photographers will run
programs that predict the passage of these objects so as to avoid them.
Obviously, most amateur astronomers look upon these satellites as just
one more step along the slippery road of increased light pollution.
On the other hand, we have an opportunity here to make lemonade out of
lemons. The Star Wars generation has been hard to impress with telescopic
views of deep sky objects, and our explanations of the vastness of the
universe. They are attune to exploding death stars and celestial dogfights.
Their WOW factor is set very high. Getting them to come to a dark sky
site to get wowed at the eyepiece is very difficult.
Fortunately astronomers have had a couple big wowsers in the last few
years that have attracted the interest of the public. First it was Shoemaker-Levy-9ís
title bout with Jupiter. Then it was the Comet Hale-Bopp media tour. And
the Hubble Space Telescope chimes in every six months or so with some
incredible photo that makes the network rounds. So the one time big events
have been there.
Now, with Iridium flashes, there is an ongoing predictable wowser than
can serve as a trojan horse to lure unsuspecting light pollution dwellers
into the dark and majestic world of astronomy. The Iridium satellites
could become astronomers unwitting partners in building an interest in
the night sky if they will seize the day, or should I say seize the night.
Become an expert in these objects. Learn how to predict their passage.
Wow your friends. And tickle the interest of a potential new amateur astronomer.
Or, depending on your personality, you could also predict the next UFO/government
iridium flash over your boss's house.
Some Links for Iridium Satellite
The basic Iridium information can be found here. You will also find links
to the shareware programs used to predict satellite passes.
The Iridium Satellite
The Iridium system is explained at the Iridium company web site.
Celestrak provides the two-element sets for the Iridium (and many other)
GSOC Satellite Predictions
This is a web-based satellite prediction program.
Uwe Reimann is building a site containing Iridium flash videos.
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